Sums of the additive divisor problem type are of the form \[ \sum^\infty_{n=1} a(n)a(n+f)W\left(\frac nf\right),\;f\geq 1, \] where \(a(n)\) is either the divisor function \(d(n)\) or a Fourier coefficient of a cusp form for the full modular group, and \(W\) is a smooth function of compact support on the positive reals. The author treats a third case, the Fourier coefficients of a Maass form. By the inner product method in this case a spectral summation formula for convolution sums involving Fourier coefficients of Maass forms is derived. An application to subconvexity estimates for Rankin-Selberg \(L\)-functions in announced.